JP2010066160A - Battery state detection device and battery pack incorporated therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery state detection device and a battery pack incorporated therewith, accurately providing the information to a user as to the need to change a secondary battery regardless of the cause of the deterioration of the secondary battery. <P>SOLUTION: The battery state detection device for detecting the state of the secondary battery 200 feeding an electronic instrument 300 includes: a calculation processing unit 50 for calculating the capacity degradation rate and the internal resistance value of the secondary battery 200 and for determining the need to change the secondary battery 200 when either of the calculated capacity degradation rate and the internal resistance value or both of them reaches the value at which the change of the secondary battery 200 is needed; and a communication processing unit 70 for outputting the signal in accordance with the determined result by the calculation processing unit 50. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a battery state detection device that detects a state of a secondary battery that supplies power to an electronic device, and a battery pack that includes the battery state detection device.

  With the progress of the deterioration of the secondary battery, it is expected that the operable time of the electronic device fed from the secondary battery is gradually shortened and the probability of occurrence of a malfunction such as an internal short circuit is increased. The main deterioration factor is considered to be an increase in the internal resistance value of the secondary battery. Based on this idea, the deterioration state of the secondary battery is determined by calculating the internal resistance value based on the detected value of the voltage and current of the secondary battery.

On the other hand, Patent Document 1 discloses a battery according to a value of an estimated specific capacity C / C ₀ (C is an estimated capacity of a lithium ion battery and C ₀ is a nominal capacity of a lithium ion battery) calculated as a result of deterioration determination. LEDs that provide a prompt for replacement (red is replacement, yellow will be replaced soon, green is not required to be replaced) are disclosed.
JP 2001-289924 A

  However, even if the estimated specific capacity described in Patent Document 1 is replaced with an internal resistance value and information about the necessity of replacement of the secondary battery is provided to the user according to the magnitude of the internal resistance value, charging and discharging are repeated. Depending on the deterioration factor of the secondary battery, depending on the deterioration factor of the secondary battery, the user must be accurately informed of the need for replacement of the secondary battery. Can not do it.

  Therefore, the present invention provides a battery state detection device and a battery pack that incorporates the battery state detection device that can accurately provide the user with information on the necessity of replacement of the secondary battery regardless of the deterioration factor of the secondary battery. For the purpose of provision.

In order to achieve the above object, a battery state detection device according to the present invention includes:
A battery state detection device for detecting a state of a secondary battery that supplies power to an electronic device,
A capacity deterioration rate calculating means for calculating a capacity deterioration rate of the secondary battery;
An internal resistance value calculating means for calculating an internal resistance value of the secondary battery;
Determining means for determining the necessity of replacement of the secondary battery based on the capacity deterioration rate calculated by the capacity deterioration rate calculating means and the internal resistance value calculated by the internal resistance value calculating means;
Output means for outputting a signal according to the determination result by the determination means,
The determination means includes
When one or both of the capacity deterioration rate calculated by the capacity deterioration rate calculation means and the internal resistance value calculated by the internal resistance value calculation means reach a value that requires replacement of the secondary battery, the second It is determined that the replacement of the secondary battery is necessary.

In order to achieve the above object, a battery state detection device according to the present invention includes:
A battery state detection device for detecting a state of a secondary battery that supplies power to an electronic device,
A capacity deterioration rate calculating means for calculating a capacity deterioration rate of the secondary battery;
An internal resistance value calculating means for calculating an internal resistance value of the secondary battery;
Determining means for determining the necessity of replacement of the secondary battery based on the capacity deterioration rate calculated by the capacity deterioration rate calculating means and the internal resistance value calculated by the internal resistance value calculating means;
Output means for outputting a signal according to the determination result by the determination means,
The determination means includes
The deterioration state of the secondary battery in which the capacity deterioration rate calculated by the capacity deterioration rate calculation means and the internal resistance value calculated by the internal resistance value calculation means are reflected as factors determining the deterioration state of the secondary battery. A deterioration state quantity representing the above is calculated, and when the calculated deterioration state quantity reaches a value that requires replacement of the secondary battery, it is determined that replacement of the secondary battery is necessary.

  In order to achieve the above object, a battery pack according to the present invention incorporates the battery state detection device and the secondary battery.

  According to the present invention, it is possible to accurately provide the user with information on the necessity of replacement of the secondary battery regardless of the deterioration factor of the secondary battery.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of an intelligent battery pack 100A that is an embodiment of a battery pack according to the present invention. The battery pack 100A includes a temperature detection unit 10 that detects the ambient temperature of the secondary battery 200 such as a lithium ion battery, a nickel metal hydride battery, and an electric double layer capacitor, a voltage detection unit 20 that detects the voltage of the secondary battery 200, A current detection unit 30 that detects a charging / discharging current of the secondary battery 200, an AD converter (hereinafter referred to as "ADC") 40 that converts an analog voltage value output from each detection unit indicating a detection result into a digital value, An arithmetic processing unit 50 (for example, a microcomputer including a CPU 51, a ROM 52, a RAM 53, etc.) that performs arithmetic processing such as current integration, capacity correction, and dischargeable capacity, and a secondary battery 200 and a battery pack 100A used for the arithmetic processing. A memory 60 (for example, storing characteristic data for specifying the characteristics of each component of the battery pack and unique information of the battery pack 100A) , A storage device such as an EEPROM or a flash memory) and a communication processing unit 70 (for example, a communication IC) that transmits battery information such as a battery state related to the secondary battery 200 to the portable device 300 that uses the secondary battery 200 as a power source. ), A timer unit 80 for managing the time, and a start-up current detection unit 31 for detecting the start-up current of the portable device 300 according to the detection result of the current detection unit 30, a management for managing the battery state Built in as a system. Some or all of these components of the battery state detection device may be constituted by an integrated circuit. The mobile device 300 includes a display unit 310 such as a display as information providing means for providing information to the user.

  The battery pack 100A is a module component that combines the secondary battery 200 and a management system that manages the battery state. The battery pack 100 </ b> A is connected to the mobile device 300 via the electrode terminals (the positive terminal 1 and the negative terminal 2) and the communication terminal 3. The positive electrode terminal 1 is electrically connected to the positive electrode of the secondary battery 200 via an energization path, and the negative electrode terminal 2 is electrically connected to the negative electrode of the secondary battery 200 via an energization path. The communication terminal 3 is connected to the communication processing unit 70. The communication processing unit 70 is an output unit that outputs transmission information based on the processing result of the arithmetic processing unit 50 to the portable device 300.

  The portable device 300 is an electronic device that can be carried by a person, and specifically includes a mobile phone, an information terminal device such as a PDA or a mobile personal computer, a camera, a game machine, a player such as music or video, and the like. The battery pack 100A is built in or externally attached to the mobile device 300. The mobile device 300 performs a predetermined operation according to the battery information based on the battery information such as the battery state acquired from the communication processing unit 70. For example, the portable device 300 displays battery state information on a display unit such as a display (for example, displays remaining amount information, deterioration information, replacement time information, etc. of the secondary battery 200), or based on the battery state information. (E.g., change from the normal power consumption mode to the low power consumption mode).

  The secondary battery 200 is a power source for the portable device 300, and is also a power source for the ADC 40, the arithmetic processing unit 50, the communication processing unit 70, and the timer 80. Moreover, about the temperature detection part 10, the voltage detection part 20, the current detection part 30, and the starting current detection part 31, the electric power feeding from the secondary battery 200 may be needed according to those circuit structures. As for the memory 60, the stored contents are retained even when the power supply from the secondary battery 200 is cut off. The temperature detection unit 10, the voltage detection unit 20, the current detection unit 30, the ADC 40, and the arithmetic processing unit 50 function as a state detection unit that detects the battery state of the secondary battery 200.

  The temperature detection unit 10 detects the ambient temperature of the secondary battery 200, converts the detected ambient temperature into a voltage that can be input to the ADC 40, and outputs the converted voltage. The digital value of the battery temperature indicating the ambient temperature of the secondary battery 200 converted by the ADC 40 is transmitted to the arithmetic processing unit 50 and used as a parameter for the arithmetic processing. The digital value of the battery temperature is converted into a predetermined unit by the arithmetic processing unit 50 and is output to the portable device 300 through the communication processing unit 70 as battery state information indicating the battery state of the secondary battery 200. The Note that, since the secondary battery 200 is built in the battery pack 100A, the temperature detection unit 10 detects the temperature of the secondary battery 200 itself and the ambient temperature as the temperature of the battery pack 100A and its components. Good.

  The voltage detection unit 20 detects the voltage of the secondary battery 200, converts the detected voltage into a voltage that can be input to the ADC 40, and outputs the voltage. The digital value of the battery voltage indicating the voltage of the secondary battery 200 converted by the ADC 40 is transmitted to the arithmetic processing unit 50 and used as a parameter for the arithmetic processing. In addition, the digital value of the battery voltage is converted into a predetermined unit by the arithmetic processing unit 50, and is output to the portable device 300 via the communication processing unit 70 as battery state information indicating the battery state of the secondary battery 200. The

  The current detection unit 30 detects the charge / discharge current of the secondary battery 200, converts the detected current into a voltage that can be input to the ADC 40, and outputs the voltage. The current detection unit 30 includes a current detection resistor 30a connected in series with the secondary battery 200 and an operational amplifier that amplifies the voltage generated at both ends of the current detection resistor 30a. The current detection resistor 30a and the operational amplifier are used to charge and discharge current. To voltage. The operational amplifier may be provided in the ADC 40. The digital value of the battery current indicating the charging / discharging current of the secondary battery 200 converted by the ADC 40 is transmitted to the arithmetic processing unit 50 and used as a parameter for the arithmetic processing. In addition, the digital value of the battery current is converted into a predetermined unit by the arithmetic processing unit 50, and is output to the portable device 300 via the communication processing unit 70 as battery state information indicating the battery state of the secondary battery 200. The

  The arithmetic processing unit 50 calculates the remaining capacity of the secondary battery 200. Any appropriate method may be used as the remaining capacity calculation method, and the calculation method is exemplified below.

  The arithmetic processing unit 50 integrates the current value detected by the current detection unit 30 in a charged state or a discharged state of the secondary battery 200 (for example, a state where a current of a predetermined value or more is consumed by the operation of the portable device 300). As a result, the amount of electricity charged and discharged in the secondary battery 200 can be calculated, and the current amount of electricity (remaining capacity) stored in the secondary battery 200 can be calculated. In calculating the remaining capacity, for example, Japanese Patent Application Laid-Open No. 2004-226393 discloses that charging / discharging efficiency does not change when conditions such as temperature and current change in charging / discharging of a secondary battery, There is disclosed an idea that there is an amount of electricity that cannot be temporarily charged or discharged according to conditions, and the amount changes. According to this concept, the correction process for the charge / discharge efficiency may not be performed.

  However, when there is a temperature-dependent circuit unit that depends on temperature in the constituent parts of the battery pack 100A, the arithmetic processing unit 50 detects the ambient temperature by the temperature detection unit 10 and obtains the “charge / discharge current-temperature” characteristic. Based on this, the charge / discharge current value of the secondary battery 200 converted by the ADC 40 may be corrected. The “charge / discharge current-temperature” characteristic is represented by a correction table or a correction function. Data in the correction table and coefficients of the correction function are stored in the memory 60 as characteristic data. The arithmetic processing unit 50 corrects the charge / discharge current value according to the temperature measured by the temperature detection unit 10 in accordance with a correction table or correction function reflecting the characteristic data read from the memory 60.

  On the other hand, when the charging / discharging of the secondary battery 200 is in a dormant state (for example, the operation of the portable device 300 is stopped or in a standby state), the charging current value is smaller than that in the charging state or the discharging state. As a result, if the measurement by the current detection unit 30 or the ADC 40 includes a lot of errors or the measurement is impossible for a certain period due to reasons such as resolution, an error in the above-described current integration process for calculating the remaining capacity. Is accumulated, the accuracy of remaining capacity calculation is lost. In order to prevent this, the arithmetic processing unit 50 may stop the current value integration process or store the current consumption value of the portable device 300 measured in advance in the memory 60 and integrate the values. .

  In addition, in order to increase the calculation accuracy such as the remaining capacity and the charging rate, the calculation processing unit 50 periodically measures the voltage (open voltage) of the secondary battery 200 when the portable device 300 is in a suspended state for a predetermined time. The charge rate is calculated and corrected based on the “open-circuit voltage-charge rate” characteristic (see FIG. 5). The open circuit voltage is a voltage between both electrodes measured with a high impedance or between the electrodes of the stable secondary battery 200 opened. The charging rate means a percentage of the remaining capacity of the secondary battery 200 displayed in% when the full charge capacity of the secondary battery 200 at that time is 100. The “open-circuit voltage-charge rate” characteristic is represented by a correction table or a correction function. Data in the correction table and coefficients of the correction function are stored in the memory 60 as characteristic data. The arithmetic processing unit 50 calculates and corrects the charging rate corresponding to the open-circuit voltage measured by the voltage detection unit 20 in accordance with a correction table or correction function reflecting the characteristic data read from the memory 60.

  Moreover, when the temperature characteristic exists in the open circuit voltage of the secondary battery 200, the arithmetic processing unit 50 may perform a predetermined temperature correction on the open circuit voltage. For example, the arithmetic processing unit 50 may detect the ambient temperature by the temperature detection unit 10 and correct the open-circuit voltage of the secondary battery 200 converted by the ADC 40 based on the “open-circuit voltage-temperature” characteristic. The “open voltage-temperature” characteristic is represented by a correction table or a correction function. Data in the correction table and coefficients of the correction function are stored in the memory 60 as characteristic data. The arithmetic processing unit 50 corrects the open-circuit voltage according to the temperature measured by the temperature detection unit 10 according to a correction table or correction function reflecting the characteristic data read from the memory 60.

  As described above, the arithmetic processing unit 50 can calculate the charging rate of the secondary battery 200, but the remaining capacity of the secondary battery 200 can be calculated based on the relationship between the full charge capacity and the charging rate. Therefore, the remaining capacity of the secondary battery 200 cannot be calculated unless the full charge capacity of the secondary battery 200 is measured or estimated.

  As a method of calculating the full charge capacity of the secondary battery 200, for example, there are a method of calculating based on the discharge amount of the secondary battery 200 and a method of calculating based on the charge amount. For example, when the calculation is based on the charge amount, charging is performed at a constant voltage or constant current except for pulse charging, so that the calculation is based on the discharge amount that is easily influenced by the current consumption characteristics of the mobile device 300. Accurate charging current can be measured. Of course, which method is to be used may be selected in consideration of the characteristics of the mobile device 300 or both.

  However, the condition under which the full charge capacity can be accurately measured is that the battery is continuously charged from the state where the remaining capacity is zero to the full charge state, and the current value accumulated during this charge period is Fully charged capacity. However, in consideration of general usage, such charging is rarely performed, and charging is normally performed from a state where there is a certain remaining capacity.

Therefore, in consideration of such a case, the arithmetic processing unit 50 calculates the full charge capacity of the secondary battery 200 based on the battery voltage immediately before the start of charging and the battery voltage when a predetermined time has elapsed since the end of charging. To do. That is, the arithmetic processing unit 50 calculates the charging rate immediately before the start of charging based on the battery voltage immediately before the start of charging and the “open-circuit voltage-charging rate” characteristic (see FIG. 5), and at a predetermined time from the end of charging. Based on the battery voltage at the time of elapse and the “open-circuit voltage-charging rate” characteristic (see FIG. 5), the charging rate at the elapse of a predetermined time from the end of charging is calculated. Then, the arithmetic processing unit 50 sets the full charge capacity to FCC [mAh], the charge rate immediately before the start of charge to SOC1 [%], the charge rate after a predetermined time has elapsed from the end of charge to SOC2 [%], If the amount of electricity charged in the charging period up to the end of charging is Q [mAh], the calculation formula FCC = Q / {(SOC2-SOC1) / 100} (1)
Based on the above, the full charge capacity FCC of the secondary battery 200 can be calculated. If SOC1 and SOC2 are temperature-corrected, more accurate values can be calculated. Further, by using the battery voltage at the time when the predetermined time has elapsed from the end of charging, the battery voltage more stable than the end of charging can be reflected in the calculation, and the accuracy of the calculation result can be improved.

  Therefore, the remaining capacity of the secondary battery 200 can be calculated based on the charging rate and the full charging capacity calculated as described above (remaining capacity = full charging capacity × charge rate).

In addition, since the full charge capacity FCC can be calculated, the capacity deterioration rate SOH [%] of the secondary battery 200 can be estimated. When the initial full charge capacity is AFCC and the full charge capacity at an arbitrary time point is RFCC, the arithmetic processing unit 50 calculates an arithmetic expression SOH = RFCC / AFCC × 100 (2)
Based on the above, the capacity deterioration rate SOH of the secondary battery 200 at an arbitrary time can be calculated. In other words, the capacity deterioration rate SOH in the present embodiment is the degree of newness, and as is clear from the equation (2), the smaller the value, the more the secondary battery is deteriorated. Of course, in some cases, the definition of equation (2) may be rewritten to indicate that the secondary battery is more degraded as the value of the capacity degradation rate SOH is larger.

  Further, in this embodiment, the arithmetic processing unit 50 calculates the internal resistance value of the secondary battery 200. Any appropriate method may be used as a calculation method of the internal resistance value, and the calculation method is exemplified below.

  The arithmetic processing unit 50 detects and calculates the current difference of the charge / discharge current in the unit time and the voltage difference of the battery voltage in the same period as the unit time in the unit time including the charging start time of the secondary battery 200. Thus, the internal resistance value of the secondary battery 200 is calculated.

That is, the battery voltage immediately before the start of charging is V0, the charge current immediately before the start of charging is I0, the battery voltage when the specified time has elapsed since the start of charging is V1, and the charging current when the specified time has elapsed since the start of charging is I1. Then, assuming that the internal resistance value immediately before the start of charging is equal to the internal resistance value at the time when the specified time has elapsed since the start of charging, the internal resistance value Rc of the secondary battery 200 is an internal resistance value calculation formula Rc = (V1-V0) / (I1-I0) (3)
Can be calculated.

  In this regard, when the internal resistance value is calculated by substituting the current and voltage detected at each time before and after the start of charging into the calculation formula (3), the stable calculation result of the internal resistance value is Although the explanation of the result of the confirmation test conducted to confirm that it is obtained is omitted, the result of this confirmation test shows that the deterioration has progressed compared with the new product and the charge current is different even before and after the start of charging. A stable internal resistance value can be calculated based on the voltage value and current difference between the two.

  Therefore, the arithmetic processing unit 50 detects a pause state in which the charge / discharge current value of the secondary battery 200 is zero or a minute charge / discharge current flows through the secondary battery 200 for a predetermined time, and then is greater than the current value in the pause state. When a charging state in which a charging current value equal to or greater than the value is detected is detected, the voltage value and current value of the secondary battery 200 in a charging state after a predetermined time has elapsed since the detection of the charging current value equal to or greater than the predetermined value; Based on the voltage value and current value of the secondary battery 200 in the resting state before the detection time of the charging current value equal to or greater than the predetermined value, the internal resistance value of the secondary battery 200 is calculated according to the above equation (3). It is good to calculate. The arithmetic processing unit 50 can determine whether the calculated internal resistance value has decreased from its initial value (previously stored in the memory 60 or the like), thereby determining a micro short circuit of the secondary battery 200. The determination information is transmitted to the mobile device 300 via the communication processing unit 70.

  FIG. 3 is a calculation flow of the internal resistance value of the management system in the battery pack 100A. The management system operates mainly by the arithmetic processing unit 50. After initialization of the management system, the arithmetic processing unit 50 performs temperature measurement by the temperature detection unit 10, voltage measurement by the voltage detection unit 20, and current measurement by the current detection unit 30 (step 10). The arithmetic processing unit 50 detects the measurement values obtained by these detection units at a predetermined detection cycle, and stores data on the simultaneous points of the voltage value, the current value, and the temperature value in a memory such as the RAM 53. This detection cycle takes into consideration the rising characteristics of the battery voltage when charging the secondary battery 200 so that the voltage difference and current difference before and after the rising of the battery voltage when charging the secondary battery 200 can be accurately detected. To be determined.

  The arithmetic processing unit 50 detects a resting state in which a charging / discharging current value is zero or a small charging / discharging current flows by the current detection unit 30 for a certain period, and then the current detected by the current detection unit 30 is the secondary battery 200. It is determined whether or not it is equal to or greater than a predetermined positive first current threshold value for determining the start of charging (steps 10 and 12). If the current detected by the current detection unit 30 at the detection timing of step 10 is not equal to or greater than the first current threshold, the arithmetic processing unit 50 uses the detected voltage, current, and temperature as detection values immediately before the start of charging. , V0, I0, Temp are determined (step 14). After the determination, the process returns to step 10. V0, I0, and Temp are updated until the current detected by the current detection unit 30 in step 12 becomes equal to or greater than the first current threshold.

  When the current detected by the current detection unit 30 in step 10 is not equal to or greater than the first current threshold (absolute value), but is zero or a discharge current value (absolute value) greater than a predetermined value greater than zero. Assuming that the detected value is not suitable for calculating the correct internal resistance value, the detected value may be excluded as a current for calculating the internal resistance value.

  On the other hand, in step 12, when the current detected by the current detection unit 30 at the detection timing of step 10 is greater than or equal to the first current threshold value, the arithmetic processing unit 50 has started charging the secondary battery 200. Accordingly, the temperature measurement by the temperature detection unit 10, the voltage measurement by the voltage detection unit 20, and the current measurement by the current detection unit 30 are performed again (step 16). The arithmetic processing unit 50 determines whether or not the current detected by the current detection unit 30 in step 16 is greater than or equal to a predetermined second current threshold value that is greater than the first current threshold value (step 18). The second current threshold is a determination for determining whether the charging state is stable after the charging current for the secondary battery 200 rises (a charging state in which the fluctuation amount of the charging current is smaller than the rising state of the charging current). It is a threshold value.

  If the current detected by the current detection unit 30 in step 16 is not equal to or greater than the second current threshold value, the arithmetic processing unit 50 is not suitable for calculating the internal resistance value because the charging current is not yet stable after the start of charging. If there is, this flow ends. On the other hand, when the current detected by the current detection unit 30 in step 16 is equal to or greater than the second current threshold, the arithmetic processing unit 50 regards the charging current as stable and detects the detected voltage and The current is determined as V1 and I1 as detected values when the specified time has elapsed from the start of charging (step 20). If the specified time has not elapsed since the detection of a current value equal to or greater than the first current threshold value in step 22, the charging current is considered to be still rising and the process returns to step 16. On the other hand, if it has elapsed, the process proceeds to step 24. In step 24, the arithmetic processing unit 50 calculates the internal resistance value Rc of the secondary battery 200 according to the arithmetic expression (3).

  Therefore, each time the secondary battery 200 is charged, the internal resistance value Rc is calculated. As shown in FIG. 4, the first current threshold value for determining the start of charging and the first current threshold value greater than the first current threshold value are calculated. By setting the current threshold value of 2, it is possible to reliably capture the charging start time for the secondary battery 200 and use the detected value in a stable charged state for the calculation of the internal resistance value.

  Further, when the mobile device 300 operates to intermittently consume current (for example, when switching between the normal power consumption mode and the low power consumption mode is performed intermittently, the steady-state current consumption is 1 mA. If the consumption current periodically becomes 100 mA), and the rising timing of charging overlaps with the detection timing of the current I0 before starting charging or the current I1 after starting charging, the calculation error of the internal resistance value becomes large. However, in consideration of the operating state of the mobile device 300, the calculation error of the internal resistance value can be suppressed by setting the two current threshold values and calculating the internal resistance value as described above. In order to suppress the calculation error of the internal resistance value, the operation state of the mobile device 300 is taken into consideration, for example, an average value of a plurality of detection values, an average value of a large number of coincidence among the detection values of a plurality of times, The detected value or the like to be used may be adopted as a substitution value for the internal resistance value calculation formula.

  However, when the temperature characteristic exists in the constituent parts of the secondary battery 200 or the battery pack 100A, the internal resistance value Rc has the temperature characteristic. For example, the open circuit voltage of the secondary battery 200 tends to decrease as the ambient temperature increases. Further, since the temperature detection unit 10, the voltage detection unit 20, the current detection unit 30, the ADC 40, and the like include analog elements such as resistors, transistors, and amplifiers, they can be temperature-dependent circuit units. Basically, at the design stage of an integrated circuit, it is designed in consideration of the temperature dependence of the elements in the wafer. However, since there are variations in the manufacturing process and variations in the characteristics in the wafer surface, it was manufactured to a small extent. The IC will have temperature characteristics.

  Therefore, using the temperature information at the time of resistance calculation, a correction operation is performed so that the calculated internal resistance values are equal regardless of the measurement temperature. The arithmetic processor 50 calculates the first corrected resistance value Rcomp by correcting the resistance value Rc calculated in step 24 according to the ambient temperature (step 26).

  Any appropriate method may be used as a method for correcting the internal resistance value by temperature. The “internal resistance value-temperature” characteristic is represented by a correction table or a correction function. Data in the correction table and coefficients of the correction function are stored in the memory 60 as characteristic data. The arithmetic processing unit 50 has a first corrected resistance value Rcomp obtained by correcting the internal resistance value Rc according to the temperature at the time of measurement by the temperature detecting unit 10 according to a correction table or correction function reflecting the characteristic data read from the memory 60. Can be calculated.

  Furthermore, since the calculated internal resistance value also changes depending on the remaining capacity of the secondary battery, correction calculation is performed so that a substantially constant internal resistance value is calculated even if the remaining capacity at the time of measurement is different. . The arithmetic processing unit 50 calculates the second corrected resistance value Rcomp2 by correcting the resistance value Rcomp calculated in step 26 according to the remaining capacity (step 28).

  Any appropriate method may be used as a method for correcting the internal resistance value by the remaining capacity. The “internal resistance value−remaining capacity” characteristic is represented by a correction table or a correction function. Data in the correction table and coefficients of the correction function are stored in the memory 60 as characteristic data. The arithmetic processing unit 50 corrects the first corrected resistance value Rcomp with the remaining capacity Q0 immediately before the start of charging according to a correction table or correction function reflecting the characteristic data read from the memory 60. Rcomp2 can be calculated. Thereby, the internal resistance value can be accurately calculated.

  By the way, secondary batteries, such as a lithium ion battery, increase an internal resistance value and a battery capacity (full charge capacity) falls by repeating charging / discharging or preserve | saving at high temperature. When the battery in such a state is continuously used, the operation time of the portable device is shortened, and it is necessary to charge frequently. In addition, the battery is expected to have a higher probability of occurrence of a malfunction such as an internal short circuit if it is used for a long period of time. Therefore, in this embodiment, as described below, a threshold is set for the rate of decrease of the full charge capacity and the internal resistance value in order to inform the user of the portable device of an appropriate battery replacement time. Therefore, the convenience of the user and the safety of the battery are improved.

  The deterioration of the battery appears from the user's standpoint as a phenomenon in which the usage time decreases, but it appears as the deterioration of the electrolyte and the electrode inside the battery, and shows different characteristics. Deterioration due to repeated charge and discharge appears as a change in the characteristics of the electrolyte, and in this case, the internal resistance value increases only slightly. On the other hand, deterioration due to high temperature storage appears as electrode deterioration, and in this case, an increase in internal resistance value is observed. This point will be described with reference to FIG.

  FIG. 6 is a diagram showing the results of measuring the relationship between the internal resistance value and the remaining capacity due to the difference in the deterioration factor and the deterioration state of the lithium ion battery. The internal resistance value and the remaining capacity are measured by the method described above. “80% Chg” indicates the result of measurement for a battery whose capacity deterioration rate was adjusted to 80% due to storage deterioration, and “70% Chg” was measured for a battery whose capacity deterioration rate was adjusted to 70% due to storage deterioration. “60% Chg” indicates the result of measurement for a battery whose capacity deterioration rate is adjusted to 60% due to storage deterioration, and “fresh Chg” indicates a battery with a capacity deterioration rate of 100% (ie, a new battery). The result measured about is shown. Further, “1400 cycle Chg” indicates a result of measurement performed on a battery that has been charged and discharged 1400 times.

  Looking at the battery due to storage deterioration, the internal resistance value of the battery having a capacity deterioration rate of 60% (actually 63.9%) is in the vicinity of 600 mΩ. The capacity deterioration rate of 63.9% is a value when the lower limit voltage of the battery specification of the test product is 2.75 V. Therefore, the usable capacity decreases as the lower limit voltage increases. Assuming that the lower limit voltage required for is 3.4 V, the capacity deterioration rate corresponds to 53.4%. Therefore, if it is assumed that the capacity deterioration rate is 50% when the secondary battery needs to be replaced, if the internal resistance value is an index for determining when the secondary battery needs to be replaced, 600 mΩ is secondary. This corresponds to the time when the battery needs to be replaced. That is, by setting the threshold value of the internal resistance value to 600 mΩ, it can be used as a guide when the secondary battery is replaced with respect to storage deterioration.

  Further, the internal resistance value at which the capacity deterioration rate is approximately the same as the storage deterioration due to cycle deterioration is 240 mΩ, and it was found from the test results of FIG. 6 that the internal resistance value did not increase much compared to the new case. Therefore, with regard to cycle deterioration, since it is difficult to determine deterioration based only on the internal resistance value, deterioration determination based on the capacity deterioration rate may be performed. For example, by setting the capacity deterioration rate to 50%, the threshold for capacity deterioration due to cycle deterioration is set.

  Replacement time point determination threshold value that specifies the value of capacity deterioration rate that requires replacement of the secondary battery and replacement time point determination threshold value that specifies the value of the internal resistance value that requires replacement of the secondary battery are the operating time of the mobile device and the battery. It may be set in consideration of safety.

  For example, when the necessity for replacement of the secondary battery is determined based on the capacity deterioration rate, the capacity deterioration rate indicates that the deterioration is progressing as the size thereof is reduced. If the rate is greater than the replacement time determination threshold, it is determined that replacement is not necessary, and if it is less than the replacement time determination threshold, it is determined that replacement is necessary.

  Further, the replacement time determination threshold value is considered as the final state that can be used, and the range in which the capacity deterioration rate can be taken is divided into a plurality of sections, whereby the necessity for replacement of the secondary battery can be determined step by step. For example, when the capacity deterioration rate of 50% is set as the replacement time point determination threshold, the arithmetic processing unit 50 determines that the calculated capacity deterioration rate is “normal (no replacement required)” when the calculated capacity deterioration rate is 100 to 70%. %, “Caution (requires replacement soon)”, 50-40%, “requires replacement”, 40-40%, “danger (requires immediate replacement)” To do.

  On the other hand, when determining the necessity of replacement of the secondary battery based on the internal resistance value, the internal resistance value indicates that the deterioration is progressing as the magnitude thereof is increased. When the value is smaller than the replacement time determination threshold, it is determined that replacement is not necessary, and when the value is equal to or greater than the replacement time determination threshold, it is determined that replacement is necessary.

  Similarly, it is possible to determine the necessity of replacement of the secondary battery in stages by considering the replacement time determination threshold as a usable final state and dividing the possible range of the internal resistance value into a plurality of sections. it can. For example, when the internal resistance value 600 mΩ is set as the replacement time point determination threshold, the arithmetic processing unit 50 determines that the calculated internal resistance value is “normal (no replacement required)” when the calculated internal resistance value is 100 to 300 mΩ, and when the calculated internal resistance value is 300 to 450 mΩ. Is determined to be “Caution (requires replacement soon)”, determined to be “replacement required” when 450 to 600 mΩ, and determined to be “dangerous (requires immediate replacement)” when 600 to 1000 mΩ.

  However, since there are various factors of deterioration in the actual use environment, it is considered that either the calculated capacity deterioration rate or the calculated internal resistance value reaches the replacement time determination threshold first. For this reason, the capacity deterioration rate and the internal resistance value are observed, and it may be determined that the battery replacement point is reached when one of them reaches the replacement point determination threshold first.

  That is, the arithmetic processing unit 50 determines that the secondary battery needs to be replaced when either the calculated capacity deterioration rate or the internal resistance value reaches the replacement time determination threshold value. As a result, even if the calculated value of the internal resistance value does not change so much due to cycle deterioration and the internal resistance value replacement point determination threshold value is not reached, the calculated value of the capacity deterioration rate becomes the replacement point of the capacity deterioration rate. Since the determination threshold value is reached, it is possible to reliably determine when the secondary battery needs to be replaced. Further, the arithmetic processing unit 50 may determine that the secondary battery needs to be replaced when both the calculated capacity deterioration rate and the internal resistance value reach the replacement time determination threshold value. Since the replacement time of the secondary battery is determined based on the two elements of the capacity deterioration rate and the internal resistance value, erroneous determination can be prevented as compared with the case of determination based on one element.

  In addition, when determining the necessity for replacement of the secondary battery based on the capacity deterioration rate and when determining the necessity for replacement of the secondary battery based on the internal resistance value, changes in the capacity deterioration rate and the internal resistance value depending on the deterioration factor. Therefore, the determination results are not necessarily the same (for example, when one is determined to be “caution” and the other is determined to be “replacement required”). In this case, the determination result may be determined based on the determination that the necessity for replacement is high in consideration of safety.

  In other words, the arithmetic processing unit 50 determines the “necessity of replacement based on the capacity deterioration rate” determined according to the size of the capacity deterioration rate and the “requirement level of replacement based on the internal resistance value” determined according to the size of the internal resistance value. ”And the necessity for replacement of the secondary battery is determined according to the size of the higher replacement necessity. The “necessity of replacement” indicates that the greater the value, the higher the necessity for replacement. By adopting the “necessity of replacement”, it is possible to clarify the necessity of replacement even when the numerical values cannot be simply compared, such as the capacity deterioration rate and the internal resistance value.

  Specifically, the arithmetic processing unit 50 determines “replacement necessity 1 (replacement not required)” when the calculated capacity deterioration rate is 100 to 70%, and determines “replacement necessity” when it is 70 to 50%. 2 ”(replacement is required soon)”, when it is 50 to 40%, it is determined “replacement necessity 3 (replacement required)”, and when it is 40 to 0%, “replacement necessity 4 (urgent replacement is necessary) ) ”. The arithmetic processing unit 50 determines that “replacement necessity 1 (requires no replacement)” when the calculated internal resistance value is 100 to 300 mΩ, and “replacement necessity 2 (soon to be replaced) when 300 to 450 mΩ. Necessary) ”is determined, and when it is 450 to 600 mΩ, it is determined that“ replacement necessity 3 (requires replacement) ”, and when it is 600 to 1000 mΩ, it is determined that“ replacement necessity 4 (urgent replacement is necessary) ”. For example, when the replacement necessity based on the capacity deterioration rate is “2” and the replacement necessity based on the internal resistance value is “3”, the replacement necessity of the secondary battery is determined to be “3”.

  The communication processing unit 70 outputs a signal that causes the display unit 310, which is an information providing unit for the user of the mobile device 300, to output information corresponding to the size of the higher necessity of replacement. For example, if the size of the higher replacement necessity is “2”, as shown in FIG. 2, the control unit such as the microcomputer in the portable device 300 displays “caution” as the battery replacement time on the display unit 310. The display is controlled so as to be displayed.

Further, the arithmetic processing unit 50 calculates and calculates a deterioration state amount representing the deterioration state of the secondary battery in which the calculated capacity deterioration rate and the internal resistance value are reflected as factors determining the deterioration state of the secondary battery. When the deterioration state amount reaches the replacement time determination threshold value, it may be determined that the secondary battery needs to be replaced. For example, this deterioration state quantity is
Degradation state quantity = (1 / capacity degradation rate) × weight K1 + internal resistance value × weight K2 (4)
(K1 and K2 are zero or positive numbers). By changing the weight, the degree of reflection of the capacity deterioration rate and the internal resistance value with respect to the deterioration state quantity can be changed.

  When the necessity of replacement of the secondary battery is determined based on the deterioration state quantity obtained by the arithmetic expression (4), the deterioration state quantity indicates that the deterioration is progressing as the magnitude thereof is increased. 50, it can be determined that the replacement is not necessary when the calculated deterioration state quantity is smaller than the replacement time determination threshold, and it can be determined that the replacement is necessary when the calculated deterioration state quantity is equal to or greater than the replacement time determination threshold.

  Similarly, it is possible to determine the necessity of replacement of the secondary battery in stages by considering the replacement time point determination threshold as a usable final state and dividing the possible range of the deterioration state amount into a plurality of sections. it can. For example, when the deterioration state quantity 100 is set as the replacement time point determination threshold, the arithmetic processing unit 50 determines that the calculated deterioration state quantity is “normal (replacement unnecessary)” when the calculated deterioration state quantity is 0 to 60, and when the calculated deterioration state quantity is 60 to 80. Is determined to be “Caution (requires replacement soon)”. When it is 80 to 100, it is determined to be “replacement required”, and when it is 100 to 1000, it is determined to be “danger (requires immediate replacement)”. The arithmetic processing unit 50 determines the necessity for replacement of the secondary battery according to the magnitude of the deterioration state quantity, and the degree of necessity for replacement of the secondary battery increases as the deterioration state quantity increases.

  The communication processing unit 70 outputs a signal that causes the display unit 310 serving as an information providing unit for the user of the mobile device 300 to output information corresponding to the magnitude of the deterioration state quantity. For example, if the magnitude of the deterioration state quantity is “70”, as shown in FIG. 2, the control unit such as the microcomputer in the portable device 300 displays “CAUTION” on the display unit 310 as the battery replacement time. Display control.

  Therefore, according to the above-described embodiment, it is possible to accurately provide the user with information on the necessity of replacement of the secondary battery regardless of whether the deterioration of the secondary battery is caused by storage deterioration or cycle deterioration. As a result, user convenience and battery safety are improved.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, at least one of the accumulated value of the charging time of the secondary battery and the accumulated value of the storage time of the secondary battery may be reflected in the above-described deterioration state quantity as an element that determines the deterioration state of the secondary battery. Thereby, it is possible to provide the user with more accurate information on the necessity of replacement of the secondary battery. Specific factors include the total charge time from the time of shipment, the total charge time in a low temperature state below a predetermined reference temperature, the total charge time in a high temperature state above a predetermined reference temperature, the number of days elapsed since shipment, and a high temperature And accumulated time stored at a low temperature.

1 is an overall configuration diagram of an intelligent battery pack 100A that is an embodiment of a battery pack according to the present invention. FIG. It is an example of a display by the display part 310. FIG. It is a calculation flow of the internal resistance value of the management system in the battery pack 100A. It is a sequence of charge detection. It is the figure which showed the "open circuit voltage-charge rate" characteristic in 25 degreeC. It is the figure which showed the result of having measured the relationship between internal resistance value and remaining capacity by the difference in the deterioration factor and deterioration state of a lithium ion battery.

Explanation of symbols

50 arithmetic processing unit 60 memory 70 communication processing unit 100A battery pack 200 secondary battery 300 portable device 310 display unit

Claims (7)

A battery state detection device for detecting a state of a secondary battery that supplies power to an electronic device,
A capacity deterioration rate calculating means for calculating a capacity deterioration rate of the secondary battery;
An internal resistance value calculating means for calculating an internal resistance value of the secondary battery;
Determining means for determining the necessity of replacement of the secondary battery based on the capacity deterioration rate calculated by the capacity deterioration rate calculating means and the internal resistance value calculated by the internal resistance value calculating means;
Output means for outputting a signal according to the determination result by the determination means,
The determination means includes
When one or both of the capacity deterioration rate calculated by the capacity deterioration rate calculation means and the internal resistance value calculated by the internal resistance value calculation means reach a value that requires replacement of the secondary battery, the second A battery state detection device, characterized in that it is determined that replacement of a secondary battery is necessary. The determination means includes
Determining according to the degree of necessity of replacement based on the capacity deterioration rate determined according to the size of the capacity deterioration rate calculated by the capacity deterioration rate calculating means and the size of the internal resistance value calculated by the internal resistance value calculating means The battery state detection device according to claim 1, wherein the necessity for replacement of the secondary battery is determined in accordance with a magnitude of a higher replacement degree by comparing with a replacement degree based on the internal resistance value.   3. The battery state detection device according to claim 2, wherein the output unit outputs a signal that causes an information providing unit for a user provided in the electronic device to output information corresponding to a size of the higher replacement necessity. 4. . A battery state detection device for detecting a state of a secondary battery that supplies power to an electronic device,
A capacity deterioration rate calculating means for calculating a capacity deterioration rate of the secondary battery;
An internal resistance value calculating means for calculating an internal resistance value of the secondary battery;
Determining means for determining the necessity of replacement of the secondary battery based on the capacity deterioration rate calculated by the capacity deterioration rate calculating means and the internal resistance value calculated by the internal resistance value calculating means;
Output means for outputting a signal according to the determination result by the determination means,
The determination means includes
The deterioration state of the secondary battery in which the capacity deterioration rate calculated by the capacity deterioration rate calculation means and the internal resistance value calculated by the internal resistance value calculation means are reflected as factors determining the deterioration state of the secondary battery. The battery is characterized by calculating a deterioration state quantity representing the battery, and determining that the replacement of the secondary battery is necessary when the calculated deterioration state quantity reaches a value that requires replacement of the secondary battery. Condition detection device.   The battery state detection device according to claim 4, wherein the determination unit determines whether or not the secondary battery needs to be replaced according to the magnitude of the deterioration state amount.   The battery state detection device according to claim 5, wherein the output unit outputs a signal that causes an information providing unit for a user provided in the electronic device to output information corresponding to the magnitude of the deterioration state amount.   A battery pack including the battery state detection device according to any one of claims 1 to 6 and the secondary battery.

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